Compatible Ferroelectricity, Antiferroelectricity and Broadband Emission for a Multi-Functional 2D Organic-Inorganic Hybrid Perovskite

Abstract

Two-dimensional (2D) organic-inorganic hybrid perovskites with multifunctional characteristics have potential applications in many fields, such as, solar cells, microlasers and light-emitting diodes (LEDs), etc. Here, a 2D organic-inorganic lead halide perovskite, [Br(CH<sub>2</sub>)<sub>3</sub>NH<sub>3</sub>]<sub>2</sub>PbBr<sub>4</sub> (<b>BPA-PbBr<sub>4</sub></b>, BPA = Br(CH<sub>2</sub>)<sub>3</sub>NH<sub>3</sub>, 3-Bromopropylamine), is examined for its photophysical properties. Interestingly, <b>BPA-PbBr<sub>4</sub></b> reveals five successive phase transitions with decreasing temperature, including successive paraelectric-ferroelectric-antiferroelectric phases. Besides, <b>BPA-PbBr<sub>4</sub></b> displays ferroelectricity and antiferroelectricity throughout a wide temperature range (<376.4 K) with accompanying saturation polrization (<i>P</i><sub>s</sub>) values of 4.35 and 2.32 μC/cm<sup>2</sup>, respectively, and energy storage efficiency of 28.2%, and also exhibits superior second harmonic generation (SHG) with maximum value accounts for 95 % of the standard KDP due to the great deformation of structure (3.2302*10<sup>-4</sup>). In addition, the photoluminescence (PL) of the <b>BPA-PbBr<sub>4</sub></b> exhibits abnormal red-shift and blue-shift in different phases due to a consequence of competition between electron-phonon interaction and the lattice expansion. Further, <b>BPA-PbBr<sub>4</sub></b> reveals a broadband emission accompanied by bright white light at room temperature (293 K), which is supposed to be due to self-trapped excitons. In short, the versatility of <b>BPA-PbBr<sub>4</sub></b> originates from molecular reorientation of dynamic organic cations, as well as significant structural distortion of PbBr<sub>6</sub> octahedra. This work paves an avenue to design new hybrid multifunctional perovskites for potential applications in the photoelectronic field.